This invention pertains to a plastic material handling rack having an adaptability to receive and translate parts or relatively large machine units, to be stacked vertically one rack upon another, and to be loaded into transportation vehicles such as trailers, trucks and railroad cars.
Heretofore, racks designed for carrying heavy components such as automobile engines, axles, transmissions, pumps, and other similar relatively heavy units have been built of steel. Many of these steel racks weigh well over 500 pounds and can only be moved or lifted by power-driven lift trucks.
Steel tubs, also of substantial weight, have been used in the past for carrying a large plurality of small parts of relatively small unit weight, but constituting a heavy load when such large plurality is placed in a tub rack. Steel tub racks are designed and built differently from steel racks which carry heavy components such as engines, transmissions, etc. Steel tub racks cannot be converted into engine carrying racks, nor can the latter be converted into tub racks.
Because of the substantial weight and frangibility of steel racks, their maintenance and repair costs are relatively high and, in industrial plants, relatively frequent. For safety reasons, many of these racks must be color coded, i.e., painted in a color readily visible to personnel moving about in the area of the racks. Because of the polluted atmosphere in most industrial plants or relatively severe atmospheric conditions outside of the plants, in which these racks are moved or stored respectively, the painting film applied to the steel is relatively shortlived, requiring frequent fresh coating applications.
In industrial locations, where steel racks are often piled one upon the other (and not always carefully stacked for safe support), accidents have occurred in which personnel have been injured as a result of being struck by one or more of the racks which have toppled from their elevated positions.